Oxidation/reduction-potential (orp) based wastewater treatment process and related software program

ABSTRACT

A wastewater treatment process, and related computer program, where wastewater processing decisions are to be taken based on the real-time oxidation-reduction potential (ORP) of the wastewater. ORP is a broad-ranged index and effectively indicates the biological status of water. A computer software program appropriately adds chemicals and controls aeration based on the real-time status of ORP.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority based on U.S. patent applicationSer. No. 10/421,916, now issued as U.S. Pat. No. 7,141,175, which, inturn, claimed priority from Provisional Patent Application 60/375,525filed Apr. 25, 2002. The disclosures of these priority documents isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a process for efficiently treatingwastewater, based on the oxidation-reduction potential of water followedby need-based chemical treatment guided by knowledge of chemistry of oneor more chemicals to be added at an appropriately selectedoxidation-reduction potential. The present invention also relates to acomputer program for monitoring and automatically controlling suchwastewater treatment.

BACKGROUND OF THE INVENTION

Most existing wastewater facilities are designed to collect all theinfluents in a preliminary treatment area, where large debris and solidsare screened out of the wastewater. The remaining water is allowed topass through a primary treatment area where it is subjected to chemicaltreatments (for example, addition of ferrous chloride for phosphateremoval and some polymers to facilitate floc formation). The water isthen mixed with a bacterial biomass, and passes through an aerationphase. The movement of water is then slowed down in large tanks calledsecondary clarifiers to allow settling of sludge, and the decanted wateris subsequently disinfected by various means.

Wastewater treatment decisions currently are mainly based on parameterslike pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD) etc whichare, in fact, contributing partners to a single and superior parametercalled Oxidation-Reduction Potential (ORP), which has not beenunderstood and exploited properly. Moreover, the former parameters havea narrow range and do not clearly reveal the precise biological statusof the water.

REFERENCES

-   1) Daniel O., and F. James, Practical Engineering combined with    sound operations optimize phosphorus removal. Water Engineering    Mgt., April 2002, p 22-27-   2) Khalil Atasi, Fate and Effects of Iron and Heavy Metals on the    Activated Sludge Process, A Process Engineering Literature Review    prepared for the Iron Assessment Project Committee, August 1985.

SUMMARY OF THE INVENTION

The efforts of the present inventor provide the first attempt tohighlight the potential commercial importance of Oxidation-ReductionPotential (ORP). So far, ORP has been measured as a routine, anddecisions have been made based on operators' past experience and ‘gutfeeling’ without involving any scientific logic. ORP can be logicallyincorporated into processing decisions thereby sensibly saving money.This patent teaches that the wastewater processing decisions, especiallythe chemical additions and oxygenation, be based on observation andinterpretation of ORP values on a daily basis.

More specifically, this invention relates to a process where wastewatertreatment or processing decisions, like what, when, where and how muchof chemicals, oxygen, air or other ingredients are to be added, are madeafter assessing oxidation-reduction potential status of water at thepoint of use. Its understanding not only provides an important guide formanaging any biological system (including the human body), but also canbe used as a resource management tool for processes like wastewatertreatment, where it can bring about significant procedural improvementswith real cost savings.

A computer-software program can also be prepared, according to thepresent invention, to manage the input of wastewater resources based onreal time status of ORP.

Specifically, Oxidation-Reduction Potential (ORP) is a measure ofaccumulation or deficiency of charged molecules, particularly electrons,in the biological system. In simple words, it is a measure of electronpressure (or concentration) in a solution or system. During microbialmetabolism, electrons are produced, which must preferably be removed byoxygen to produce energy by a process called oxidative-phosphorylation.In an absence of oxygen, these electrons accumulate or react with otherions to impart a negative charge, resulting in a negative ORP, measuredin millivolts (mV). Thus, a negative ORP is a clear indication that thesystem is anaerobic, and needs oxygen on a priority basis rather thanany other chemical.

FIG. 1 shows a schematic overview of a wastewater treatment facilityoperating with ORP based management of wastewater treatment, in whichnumeral 50 represents an ORP based FeCl₃ release mechanism includingonline flow meter, phosphate analyzer, ORP measuring probe, FeCl₃releasing mechanism, and related computer software/hardware, linked to acentral data control room; and numeral 60 represents ORP based cationicchemical or polymer release mechanism including online flow meter, ORPmeasuring probe and polymer release mechanism and related computersoftware/hardware, linked to a central data control room.

It is an object of the present invention to highlight the commercialimportance of ORP and its use in decisions for cost efficient processingof wastewater. A computer software program is also proposed, accordingto the present invention, to manage the resources in the wastewatertreatment plant, based mainly on in-line ORP measurements at variouspoints. It is also proposed to precondition the influents by mixing theunprocessed wastewater with high ORP water, such as water from a spring,fountain or mountainous stream, followed by a well-calculated additionof chemical to achieve the desired objective. This could conceivablylead to serious cost savings.

For a more complete understanding of the present invention, the readeris referred to the following detailed description section, which shouldbe read in conjunction with the accompanying drawings. Throughout thefollowing detailed description and in the drawings, like numbers referto like parts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overview of ORP based management of wastewater treatment.

FIG. 2 is a flowchart showing steps involved in wastewater treatment.

DETAILED DESCRIPTION

Specifically, Oxidation-Reduction Potential (ORP) is a measure ofaccumulation or deficiency of charged molecules, particularly electrons,in the biological system. In simple words, it is a measure of electronpressure (or concentration) in a solution or system. During microbialmetabolism, electrons are produced, which must preferably be removed byoxygen to produce energy by a process called oxidative-phosphorylation.In an absence of oxygen, these electrons accumulate or react with otherions to impart a negative charge, resulting in a negative ORP, measuredin millivolts (mV). Thus, a negative ORP is a clear indication that thesystem is anaerobic, and needs oxygen on a priority basis rather thanany other chemical.

Every molecule, has specific ORP (pK_(ORP), a new term designed by thepresent inventor), around which it exists in different forms indiffering proportions. For example, iron is 50% ferrous and 50% ferricat an ORP of approximately +120 mV (i.e. the pK.sub.ORP iron is +120mV). Above +120 mV, ferric ion is in dominating proportion.

The effectiveness of a molecule, therefore, will much depend upon ORPstatus of the solution to which it is being added. In other words, ifORP is not appropriate, the treatment may not only be ineffective, butmay cause adverse effects. Similarly, the use of an anionic polymer atthe negative ORP to obtain polymerization, would be ineffective.

In addition to the information provided above and based on thelaboratory observations laid out in tables below, the ORP values changewith time and weather conditions of the day. Influents to a wastewaterfacility are usually in the negative range in summer and sunny dayspresumably due to relatively high metabolic activity as compared toamount of oxygenation of influents. ORP of influent sewage is generallypositive during winter months, cold as well as wet weather and few daysthereafter, presumably be due to lesser metabolic activity during wintermonths and/or significantly higher oxygenation of water due to rain, fogor snowfall.

Addition of any negatively charged chemical or any chemical capable ofreleasing electron at a negative ORP would be ineffective till the ORPrises to a desired level. For example, an ORP of +120 mV is necessary toassure maximum benefit of any iron salt to be added with an aim ofreducing phosphate concentration in wastewater.

These facts can be better interpreted if explained with an example fromDetroit Wastewater Treatment Plant (DWWTP).

During the period between January-June 2000, the plant had numerousproblems like high Settled Volume Index (SVI) and low sludge thickening.The present inventor found that Pickle liquor (ferrous chloride) hadbeen constantly added to the primary influents to the extent of 10 ppm,with an idea of reducing the phosphate levels in the final effluent.

According to the present inventor, not only is the approach discussed inthe previous paragraph wrong, but also such a high dose is toxic tomicrobes (2), thereby killing the microbes and resulting in a highamount of ‘chemical sludge’. The operators and the management thoughtthat this way they are cleaning the water faster. The influent to DWWTPhad shown negative ORP (avg. −180 mV) for a significant number of daysin that period. Pickle liquor (3 ppm) further lowers the ORP by 80 mV.

The addition of ferrous salts under such conditions would be of littlevalue because a significant proportion of iron will continue to exist asferrous and results in carryover of soluble ferrous phosphate to thesecondary system.

Even if the ferrous chloride is added after the sewage attained an ORPof +120 mV, the final ORP would be around +40 mV, where only negligibleportion of it would be converted to ferric to form insoluble ferricphosphate. Therefore, when pickle liquor is added, more time and work isneeded to bring the water back to the desired +120 mV ORP range.

Additionally, since ferrous ions are ready to release the extra electronon them, it adds to the electron pressure (i.e. lesser ORP and higherchemical oxygen demand). It takes us away from proper conditions forfloc formation, as there is more dispersal due to additional excessivecharge. This was the cause of high SVIs and low sludge thickening.

On the other hand, 3 ppm of ferric chloride raises the ORP by 30 mV. Ifferric chloride is added after the waters have attained nearly +90 mV(possible mostly in the aeration basins), the resultant ORP would benear +120 mV, where almost 50% of the iron added to the sewage willremain as Ferric and insoluble ferric phosphate is formed. Therefore, itis easy to calculate how much iron compound should be added, just toremove the excess phosphate.

As water moves ahead, the ORP rises itself, more and more ferric isformed and the phosphate is complexed and gets settled in secondaryclarifiers. In this approach, lesser oxygenation (up to +90 mV only) andsignificantly less iron salts are needed, without violating any permitor causing any side effects.

The laboratory data indicates that aeration first followed by ORP basedferric chloride addition results in more phosphate removal withsignificantly lower dose of iron salt needed. One plant has shownsignificant cost savings with better phosphorus removal by shifting thepoint of addition of ferric chloride from primary treatment to alocation in aeration basin of the activated sludge (without anyknowledge or mention of ORP (1).

Iron salts, as being added currently to the primary influents with awrong notion of removing phosphate, have historically lead to a numberof problems at DWWTP like high Settled Volume Index (SVI)s and lowsludge thickening. There appears to be clear and manageable relationshipbetween mixed liquor suspended solids, oxidation-reduction potential ofinfluents, type of iron salt and point of its addition.

If managed properly, NPDES permissible limits of phosphate levels ineffluent can be met at least cost. This patent is the first attempt tohighlight the importance of ORP in general and its use in making theprocessing decisions based on the continuous monitoring of theOxidation-Reduction Potential (ORP) status of wastewater as this is theproper and economic way of managing this business.

Tests indicate that if three waters having different ORPs are mixed inequal ratio, the final ORP is that of the water with higher value. Thatmeans if the wastewater influent streams in any plant are mixed and thenmerged with a water of Higher ORP, the resultant ORP would be of that ofthe water added later. This would precondition the wastewatersufficiently for processing at significant savings of resources, timeand money.

3 ppm of Pickle liquor (ferrous chloride) lowers the ORP by about −80mV, taking us away from the target. Its use at negative ORP values issimply illogical in primary sedimentation as it increases the amount ofwork needed to bring the wastewater to the previous state.

Ferric chloride (3 ppm) raises ORP by about +30 mV.

Aeration (10 psi, 45 min) raises ORP by about +200 mV. Aeration alone,in other words, helps us reach the target value of +120 mV. If this isfollowed by a calculated amount of ferric chloride, phosphate removalcan be effective and economical.

When Fecl3 is added after aeration, there is at least 26% more reductionin soluble phosphate and 26% additional reduction in turbidity.

When Pickle liquor (ferrous chloride) is added before or after aeration,there is relatively lesser reduction in soluble phosphate andpractically no reduction in turbidity, because the gains in ORP due toaeration are negated by ferrous chloride.

Based on the current information, the aeration of sewage to at least +90mV followed by addition of ferric chloride and polymer, will reduce ironrequirement and will afford better effluent with lesser phosphate.However, on many days, depending on the type of influent, it may not bepossible to reach +90 mV. Practically, to maximize the effective use ofresources, an ORP of at least +50 mV must be achieved before adding anychemical.

According to this observations, some design changes can be proposed. Forexample, there should be at least three ports in each aeration basinwhere FeCl3 can be released. The nearest FeCl3 port where ORP hasreached at least +50 mV, be opened and the dosage just sufficient toneutralize the soluble phosphates in excess of NPDES allowable limits,be added. The resulting insoluble ferric phosphate will settle later insecondary clarifiers.

This way, not only an optimum amount of chemicals are used, but alsoregulatory requirements are met without contaminating the final product.

There are several ways to increase the ORP value or neutralize thecharge of water, few of them being:

i) aeration,

ii) acidification,

iii) induction of conditions to cause ion exchange with microorganisms,where microorganisms absorb electrons or negatively charged moleculesand/or release positively charged molecules,

iv) addition of adsobants of electron or negatively charged moleculesand the like.

The terms oxidation-reduction potential and zeta potential haveoverlapping meanings depending upon the situation. For wastewater whenone raises the ORP, one is also simultaneously changing the zetapotential. Since the flocs start forming near zero zeta potential, theexpression of optimizing or raising ORP may also be considered asoptimizing or raising the zeta potential of wastewater.

Supporting Data

Now I present empirical laboratory data to support the above discussion:

Table I shows that the ORP of the plant influents samples collected forMarch 30-April 26 were positive for 40% of the time during the coldmonths. During the warmer months of June and July the plant influentsORP is always negative. Of note is the increase in ORP values of thesewage as the sewage flows thorough the treatment process.

These seasonal changes must be factored-in while considering aeration aswell as chemical addition, because during cold as well as after wetweather lesser aeration and less chemical treatment would be needed. Onthe other hand, more emphasis should be put on aeration of influentsewage during sunny and hot weather to adjust ORP to a suitable level.TABLE 1 PLANT DATA AND ORP VALUES AT VARIOUS POINTS AT DWWTP PrimarySecondary Ambient Feed site influent effluent Air Precipitation Feed =pickel highs sol. P sol. P P Total Plant Date Temp. F. Weather (inches)Fe++/Fe+++ (ppm) (ppm) (ppm) removed % inflow (mgd) Mar. 30, 2000 41Part cloudy 0 Fe++ 2.9 1.2 0.28 76.7 525 Apr. 19, 2000 35 Cloudy 0 Fe++2.8 1.0 0.15 85.0 615 Apr. 13, 2000 44 Sunny 0 Fe++ 2.9 1.0 0.20 80.0576 Apr. 24, 2000 57 Sunny (4 d after rain) 0 Fe++ 2.8 0.3 0.05 83.3 797Apr. 26, 2000 60 Sunny 0 Fe++ 2.9 0.8 0.09 88.8 695 Jun. 10, 2000 64Sunny 0 Fe++ 1.9 0.8 0.22 72.5 596 Jun. 16, 2000 67 Sunny (3 d afterrain) 0 Fe++ 2.0 1.0 0.27 73.0 598 Jun. 26, 2000 72 Sunny (1 d afterrain) 0 Fe++ 2.2 0.2 0.05 75.0 1261 Jun. 29, 2000 78 Part cloudy 0 Fe++2.0 0.7 0.44 37.1 684 Jul. 06, 2000 72 Part cloudy 0 Fe++ 1.9 0.8 0.2470.0 726 Jul. 07, 2000 74 Clear sunny 0 Fe++ 2.8 0.6 0.20 66.7 680 Jul.11, 2000 67 Clear sunny 0 Fe++ 1.9 0.8 0.20 75.0 663 Jul. 13, 2000 76Part cloudy 0 Fe++ 2.0 1.0 0.20 80.0 573 ORP Values PS2A, 500 ft Awayfrom Jeff. Oak. NIEA mixing point PEAS 1 C2E3 C2E4 Tap water Mar. 30,2000  190 205 165 Apr. 19, 2000 −116 74 17 Apr. 13, 2000  −81 65 22 144152 452 Apr. 24, 2000  110 119 107 152 149 444 Apr. 26, 2000 −112 136 48Jun. 10, 2000 −115 Jun. 16, 2000 −158 −155 −152 Jun. 26, 2000  −48  −22−113 Jun. 09, 2000 −118 −116 −123 10 Jul. 06, 2000 −173 −105 −170 −12Jul. 07, 2000  −63 −191 −201 21 65 Jul. 11, 2000  −90 −157 62 Jul. 13,2000 −140 −137 −174 102 14 Average ORP −> −117 −117  −93.4Negative ORPs are shown in bold

Table 2 confirms that aeration alone raises the ORP of influent sewageby about 195.+/−.29 units, depending upon quality of the influent eachday. TABLE 2 Effect of Aeration on ORP Date of Initial Aeration FinalChange in Experiment ORP (mV) time 10 psi ORP (mV) ORP (mV) Sep. 03,2000 −185.4 30 min 37.7 223.1 Sep. 07, 2000 −187 15 min 15.0 202 Oct.31, 2000 −186.3 30 min 22.7 209 Nov. 02, 2000 −164.5 45 min 19.5 184Nov. 09, 2000 −192.1 45 min 45.2 237.3 Jan. 15, 2002 −7.2 15 min 133.5140.7 Jan. 18, 2002 −122.6 15 min 75.9 198.5 Jan. 24, 2002 −136.1 15 min33.3 169.4 Feb. 08, 2002 −110.1 15 min 77.0 187.1 Average change in ORP194.6 Standard Deviation → 28.8

Table 3 indicates that:

a) When waters with different ORP values are combined in equal ratio,the final ORP is equal to that of having highest value. This fact is ofhigh commercial value.

b) Just as protons are added through acidification, the electronconcentration is reduced and ORP rises. This proves that it is mainlythe electron concentration that is indicative of ORP status of water.The rise in pH due to aeration is unique and has not been described inliterature and as such cannot be explained at this time.

c) The pH of influents was around 7.4 and the ORP is negative. As perour experience, nothing should happen if iron and polymers are added atthis stage. It appeared that attainment of an optimum ORP is essentialto wastewater processing as the turbidity (NTU) got lowered only whenferric chloride and polymer were added near +122 mV. This confirms thatdecisions based solely on pH may not yield the desired results. TABLE 3THE EFFECT OF COMBING SAMPLES, AERATION & POLYMER ADDITION ON pH AND ORPORP pH NTU OAKWOOD INFLUENT −157.5 7.45 NA JEFFERSON INFLUENT −186.17.20 NA OAKWOOD + JEFF 1:1 −158.0 7.44 NA NIEA INFLUENT −192.1 7.34 NAORP AFTER COMBINING OAKWOOD, −155.2 7.44 49.0 JEFFERSON, & NIEA 1:1:1AFTER AERATION 45 MINUTES, 10 psi 45.2 8.63 45.9 AFTER POLYMER 250 ul45.2 8.63 NA AFTER POLYMER, additional 250 ul 45.0 8.63 43.5 10% HCl topH 7.00 (1100 ul was needed) 122.7 7.00 44.0 Fe+++ 50 ul 118.3 NA 50.0PS2A, polymer, additional 250 ul 105.7 NA 18.3

Table 4 indicates that limited aeration is better than excessiveturbulence. Too much aeration might worsen the quality of effluent. Alsoit shows that excessive ferric chloride is of no additional use. TABLE 4EXPERIMENT TO SEE HOW MUCH AERATION IS REQUIRED Dated Sept. 03, 2000These three were additionally blended at high speed for 1 min Beaker 2Beaker 3 Beaker 4 Beaker 5 Beaker 6 Beaker 1 Aerated 30 min 10 psiAerated 30 min 10 psi Aerated 30 min 10 psi Aerated 30 min 10 psiAerated 30 min 10 psi Raw Sample FeCl3 300 μl FeCl3 150 μl none FeCl3100 μl FeCl3 150 μl Undisturbed PS2A Polymer 250 μl PS2A Polymer 250 μlnone PS2A Polymer 250 μl PS2A Polymer 250 μl ORP (mV) −156.5 −43.1 −4723 67.3 36.2 Turbidity 83.5 6.7 6.5 109* 18.7* 41.4**The turbidity is high after blending probably due to the microbubblingduring high turbulence of the blender. An impractical situation

Tables 4 and 5 show that there is significant rise in ORP by aerationalone. In this sample, only the ferric chloride and polymer addition wasenough to get an effluent with a low turbidity (Beaker 1.2 & 3). Thisis, however, not always true, as effluents on some days will not yieldat all (see Table 6). This experiment also indicates that, aerate ornot, the excessive amount of ferric has a non-significant effect on ORPor turbidity. TABLE 5 EXPERIMENT TO SEE IF AERATION FIRST IS REALLYBENEFICIAL Sept. 07, 2000 Beaker 2 Beaker 3 Beaker 4 Beaker 5 Beaker 6Raw Sample Raw Sample Aerated 15 min Aerated 15 min Aerated 15 minBeaker 1 FeCl3 50 μl FeCl3 100 μl none FeCl3 50 μl FeCl3 100 μl RawSample PS2A Polymer 250 μl PS2A Polymer 250 μl none PS2A Polymer 250 μlPS2A Polymer 250 μl ORP −187 −131 −110 15 32 42 Turbidity 95 24.5 13.785 23.5 11.4Phosphates were not studied

Tables 2, 4, 5, 6, 7, 8 & 9 establish that the aeration alone raises theORP sufficiently enough to prepare conditions for ferric chloride towork. TABLE 6 THE EFFECT OF AERATION FIRST ON PHOSPHATES Jan. 15. 2002Beaker 1 Beaker 2 Beaker 3 Raw sample Raw sample Raw sample Beaker 4Beaker 5 Beaker 6 Undisturbed Undisturbed Undisturbed Aerated 15 minAerated 15 mm Aerated 15 min none FeCl3 50 μl FeCl3 100 μl none FeCl3 50μl FeCl3 100 μl Chemical addition Wait 5 min Wait 5 min Wait 5 min Wait5 min Wait 5 min Wait 5 min ORP (mV) −7.7 26.5 ND* ND 133.5 ND Turbidity96.5 95.2 ND ND 93.5 ND Total P 0.12 0.06 ND ND 0.04 NDThe starting ORP was already high as expected because the sample was notbrought air tight.ND* = Not determined, because the sample was highly colloidal and nophysical change was observable.

Table 7 represents a sample where phosphates were lowered just byaddition of ferric chloride and that aeration after this has acumulative effect and phosphates are lowered further. This supports thehypothesis that given a fixed iron dose, more ferric ions are madeavailable as a result of increase in ORP. In the non-aerated samples,ORP is raised just by addition of ferric salts. TABLE 7 ROLE OF FERICCHLORIDE, WITH OR WITHOUT AERATION Jan. 18, 2002 Beaker 1 Beaker 2Beaker 3 none FeCl3 50 μl FeCl3 100 μl Beaker 4 Beater 5 Chemicaladdition Raw sample Raw sample Raw sample FeCl3 50 μl FeCl3 100 μlAction Undisturbed Undisturbed Undisturbed Aerated 15 min Aerated 15 mmORP = −122.6 mV Wail 10 min Wait 10 min Walt 10 min Wait 10 min Wail 10min ORF −117.3 −82 38.5 75.9 91.8 Sol. P (Avg. of 2) 0.11 0.09 0.060.045 0.035 Calculated sol P (×51) 5.61 459 3.06 2.295 1.785 Turbidity(NTU) 51.5 47.1* 19.2* 13.3 7.2*floc like ppts were settling 5 min after addition of FeCl3Contractor supplied FeCl3 solution was used (PVS Tech PJST #28358-4 dtd1-/31/00 stored at RT)

Table 8 confirms that if ferric chloride is added after aeration

a) Lesser amount of FeCl3 is needed to remove phosphate and that theexcessive use is unnecessary; and

b) ORP is additionally increased by a significant amount, while solublePhosphate and turbidity are reduced. TABLE 8 EFFECT OF REVERSING THESEQUENCE OF IRON ADDITION AND AERATION Feb. 19, 2002 IN DUPLICATE INDUPLICATE Beaker 1 Beaker 2 Beaker 3 Beaker 4 Beaker 5 BLANK IRON FIRSTIRON FIRST AERATION FIRST AERATION FIRST None FeCl3 30** μl FeCl3 30**μl AIR 10 psi 30 min AIR 10 psi 30 min stirred slowly 30 min AIR 10 psi30 min AIR 10 psi 30 min FeCl3 30** μl FeCl3 30** μl Initial ORP =−119.6 mV 290 μl 290 μl 290 μl 290 μl 290 μl PS2A POLYMER Wait 1 hr Wait1 hr Wait 1 hr Wait 1 hr Wait 1 hr Change ORP after 1 hr −45.3 101.8111.5 134.6 134.2  26% Sol. P (Avg. of 2) 0.825 0.54 0.53 0.41 0.38Calculated sol P (×7) 5.775 3.78 3.71 2.87 2.66 −26% Turbidity after 1hr 51.1 30.7 35.1 22.6 26.4 −26%Aeration was done through four new ceramic filter cartridges, so thatthe other two beakers do not have to wait for 30 min.All the beakers got similar treatments w

to

.Contractor supplied (FRESH) FeCl3 solution was used (PVS TECH #39433-1of Feb. 04, 2002)Exactly 1 ml sample was filtered through .45 μm syringe filters and allwas added so tube for sol P determination.

Table 9. This table represents the effect of adding pickle liquor beforeand after aeration. Normally, pickle liquor has often been seen to lowerthe ORP by approximately 80 units but in this sample it didn't. However,the relative gain in ORP by aeration was lesser than that with FeC13 intable 8 above. The phosphorus got removed possibly due to small portionof ferric formed at specified ORP, but it does not reduce the overallturbidity of the resulting solution. Even aeration didn't have anyeffect. Again, excessive use of pickle liquor had no additional benefit.TABLE 9 ROLE OF PICKEL LIQUOR, WITH OR WITHOUT AERATION Jan. 24, 2002Beaker 1 Raw sample Beaker 2 Beaker 3 Beaker 4 Beaker 5 Chemicaladdition None Pickel Liqor 50 μl Pickel Liqor 100 μl Pickel Liqor 50 μlPickel Liqor 100 μl Action Undisturbed Undisturbed Undisturbed Aerated15 min Aerated 15 min Initial ORP = −136.1 Wait 10 min Wait 10 min Wait10 min Wait 10 min Wait 10 min ORP −121.2 −127.6 −130.5 3.3 −37.5 Sol. P(Avg. of 2) 0.14 0.12 0.07 0.075 0.07 Calculated Sol P (×14) 1.96 1.680.98 1.05 0.98 Turbidity 87.1 86.3 92.6 86.1 88.5Contractor supplied Pickel liqor solution was used (PVS Tech T/T 109 24ADTDExactly 1 ml sample was filtered through .45 μm syringe filters and 500μl of filterate was taken for sol P determination.

Although the present invention has been described herein with respect toa limited number of presently preferred embodiments, the foregoingdescription is intended to be illustrative, and not restrictive. Thoseskilled in the art will realize that many modifications of the preferredembodiment could be made which would be operable. All suchmodifications, which are within the scope of the claims, are intended tobe within the scope and spirit of the present invention.

1. A computer software program which is usable in treating wastewater,wherein said software is executable to carry out process steps of: a)monitoring an oxidation-reduction potential (ORP) of wastewaterinfluents over time at a plurality of processing stages using aplurality of ORP sensors, said plurality of processing stages comprisinga first stage before the influents enter a water treatment facility anda second stage inside of the water treatment facility; b) optionally,aerating said influents to raise the ORP thereof if the sensed ORP atthe first stage is below a target ORP range; and c) modifying theinfluents, as needed, based on the sensed ORP of the wastewater.
 2. Thecomputer software program of claim 1, wherein the modifying stepcomprises adding a calculated amount of oxygen to the influents.
 3. Thecomputer software program of claim 1, wherein the modifying stepcomprises adding a calculated amount of polymer to the influents.
 4. Thecomputer software program of claim 1, wherein the modifying stepcomprises adding a calculated amount of ferric chloride to theinfluents.
 5. The computer software program of claim 1, wherein themodifying step comprises adding a calculated amount of at least oneadditive selected from the group consisting of oxygen, polymer, andferric chloride to the influents.